1. Field of the Invention
The present invention relates to a DNA fragment having a gene derived from fish which codes for a polypeptide possessing transglutaminase activity, a recombinant plasmid comprising a fish-derived DNA fragment which codes for a transglutaminase, a transformant into which a recombinant plasmid comprising a fish-derived DNA fragment which codes for a transglutaminase is introduced, and a method for the production of a transglutaminase, comprising culturing a transformant containing a fish-derived DNA fragment which codes for a transglutaminase.
2. Discussion of the Background
Transglutaminase (hereafter abbreviated as "TGase") is an enzyme which catalyzes an acyl group transfer reaction of a gamma-carboxyamido group of a glutamine residue in a peptide chain. In the presence of transglutaminase, an epsilon-amino group of a lysine residue in a protein functions as an acyl receptor, thus forming epsilon-(gamma-Gln)-Lys crosslinkings in the protein, or if the lysine and glutamine residues are in two or more protein molecules, epsilon-(gamma-Gln)-Lys bridges are formed between the proteins. Alternatively, if a primary amine such as an amino acid, amino acid derivative, etc. functions as an acyl receptor, transglutaminase introduces the primary amine into the protein. Also, when water functions as an acyl receptor, transglutaminase enzyme catalyzes the deamidation or hydrolysis of a glutamine residue to a glutamic acid residue.
TGase is used in the production of gelatinous food products and cosmetics, as well as yogurt, jelly and cheese, etc. (Japanese Patent Publication 50382/1989). Further, it is used for the production of materials for thermostable microcapsules, carriers for immobilized enzymes, etc.
A calcium (Ca.sup.2+)-independent TGase from bacteria of the genus Streptoverticillium has been discovered. Some concrete examples of bacteria belonging to this genus include Streptoverticillium griseocarneum IFO 12776, Streptoverticillium cinnamoneum sub sp. cinnamoneum IFO 12852, Streptoverticillium mobaraense IFO 13819, etc. (Japanese Patent Application Publication 27471/1989).
Further, TGases derived from certain mammalian animals are also known. These include a TGase derived from guinea pig liver (Connellan, et al., Journal of Biological Chemistry, Vol. 246, p. 1093-1098, 1971), from human or bovine vascular endothelial cells (Gentile, et al., Journal of Biological Chemistry, Vol. 266, p. 478-483, 1991, and Nakanishi, et al., European Journal of Biochemistry, Vol. 202, p. 15-21, 1991), and from human blood coagulation factor XIII (Takahashi, et al., Proc. Natl. Acad. Sci. USA, Vol. 83, p. 8019-8023, 1986).
Heretofore, the sources of TGase available for industrial use have been mammals and bacteria. However, the products with which TGase processing are most common include processed marine (fish) products, a typical example of which is a boiled fish paste known as "kamaboko" (Seki, et al., Nippon Suisan Gakkaishi, Vol. 56, p. 125-132, 1990). The TGase believed to be responsible for the properties of "kamaboko" is apparently an enzyme derived from fish, present in the raw fish materials used in "kamaboko" preparation.
Prior to the present invention, no information has been available concerning a TGase gene from fish. However, a TGase from fish will both widen the range of TGase use and provide enzyme-processed fish products having similarities to natural fish products. Thus, the cloning, identification and expression of a fish TGase gene is highly desired, and may lead to a supply of fish-derived TGase at a low price.